Oil burner control



Feb. 28, 1933. J EATON 1,899,563

OIL BURNER CONTROL Filed June 22, 1931 Inventov: John Eaton,

b3 M i 7km His Attorneg.

35 constant for maximum Patented Feb. 1933 UNITED STATES PATENT OFFICEJOHN EATON, OI SCHENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRICCOMPANY, A CORPORATION OF NEW YORK OIL BURNER CONTROL Application filedJune 22,

My invention relates to improvements in mixing devices, moreparticularly to fuel mixing devices for oil burners.

It has been found that if the ordinary form of oil burner is adjusted toobtain the proper air and oil mixture for the best combustion duringnormal operation, of the mixture failing to ignite when the equipment isstarted cold. I the equipment is so adjusted that when started cold theproper mixture of oil and air is supplied to insure combustion, then atother times the burner is not operating at best eificiency. Anotherdifiiculty prevalent in many oil burners is the after-fire which causessmoke when the burner is shut down. This is due to the fact that theblower and oil pump are shut down .simultaneously and the oil insuspension is provided with insuflicient combustion air for totalcombustion.

Hence it is a principal object of my invention to rovide an oil burnerwith automatic means fdr varying the fuel mixture so as to provide arich fuel mixture upon starting to insure ignition and thereafter reducethe richness of the mixture to obtain increased efliciency aftercombustion has been established.

It is another object of my invention-to insure complete combustion inthe oil burner when shutting down the oil burner.

A still furtherobject of my invention is to provide a variable flame oilburner while maintaining the proportions of oil and air efliciencybetween limits.

Briefly, one form of my invention for controllin combustion in an oilburner consists of a dlfferential drive for the oil pump and the airblower. The air blower has attached thereto a flywheel so that anappreciable torque is required to start it before full blower speed isattained. The oil pump on the other hand due to its low moment ofinertia tends to attain more than normal speed on starting so that theamount of oil supplied to the air will cause a rich mixture which iseasily i ited. As the inertia of the flywheel is gra ually overcome bythe differential drive the blower will rotate faster and the there is aliability 1931. Serial 1T0. 545,903.

pump will slow down. A balance will result so that the properproportions of oil and air are sitilpplied to the oil burner furnace forbest e ciency.

By adjusting a control valve the amount of oil pumped by the oil pumpcan be decreased. This decreased load on the pump results in an increasein the pump speed. But as the pump speed increases the blower speed, dueto the differential drive, decreases. Thus both the oil and air aredecreased in such proportions as to maintain a constant ratio betweenthe two betweenwide limits. A variable flame is thereby provided havinga very high combustion efliciency.

The drawing represents one embodiment of my invention.

In the drawing, the oil burner furnace 10 has mounted therein thefirepot 11. A blower 12 and an oil pump 14 furnish air and oil to thefirepot 11, the oil being pumped through the conduit 14' and being mixedwith the air from the blower 12 in the mixing chamber 12.

The driving motor for driving the blower 12 and the oil pump 14 is atype of induction motor in which both the rotor and the frame rotate.The frame 15 which carries the squirrel cage windings 15' rotates in thebearings 21 and 22 and the rotor 16 which carries the field windingsrotates in the bearings carried by the frame 15. It is of courseunderstood that the field windings could be carried by the frame insteadof by the rotor and that the squirrel cage could be placed on the rotor.Energy is supplied to the rotor 16 of the driving motor through theelectrical supply conductors 23 and 24. The inner slip rings 16'connected to the field windings are electrically connected to rings 23'and 24 by suitable brushes 16 The 90 rotor 16 also carries a split phasewindin for starting which is opened by centrif u al switch 26 whenrunning speed is attaineddiy rotor 16. The rotor 16 drives a pulley 18which by means of the driving belt 20 drives pulley 19 attached to theoil pump 14. The frame 15 is connected to drive the blower 12 mounted onthe shaft 17 which also carries the flywheel 13.

The relative speed between the rotor and 100 frame is slightly less thansynchronous speed.

which would be the speed of the rotor if the frame were heldstationary,'the variation from synchronous speed of course being due 5to the slip resulting from the torque on the motor. By adjusting therelative torque of the blower and the pump, any relative speed of thepump and blower can be obtained to provide a proper mixture forcombustion. One method of adjusting the torque relation is to adjust thedriving ratio between the pulleys 18 and 19 which pulleys of coursecould be readily replaced by a proper gear train.

Although any type of ignition may be used I show a gas pilot light 11for igniting the oil andair mixture.

When the driving motor is first energized due to the inertia of theblower 12 and flywheel 13, the blower 12 and flywheel 13 Wlll be broughtup to speed very slowly. However, the oil pump having very littleinertia tends to be driven at more than its normal speed by the rotor16. This causes the amount of oil initially furnished to the fur-' naceto be in much greater proportion to the air than under normal runningconditions, thus providing a rich mixture at starting which is certainto ignite. As the blower and flywheel accelerate and attain speed, thespeed of the oil pump is correspondingly reduced so that during normaloperation the blower and pump will have such relative speeds that themixture supplied to the firepot 11 will burn at maximum efliciency.

When the driving motor'is deenergized, the blower and flywheel due totheir inertia will continue to furnish combustion air at the normal ratefor a short time with a gradual decrease as the blower comes to rest,whereas the oil pump quickly stops and the oilsupply is reduced to zero.In this way suflicient combustion air is furnished until all of the oilis consumed. Consequently there is no chance for incomplete combustionand no smoke will result therefrom.

By adjusting the valve 25 to reduce the amount of oil pumped by the pump14, the load on the pump decreases. This causes an increase in the speedof pump since the torque thereon is decreased. This, however, will tendto reduce the speed of theblower so that the air and oil furnished tothe firebox 11' will be reduced in the proper proportions to maintainmaximum efliciency in combustion but providing less fuel, therebydecreasing the size of the flame. In this way a variable flame may beproduced when desired.

It will thus be seen that I have provided an oil burner wherein ignitionis assured and wherein maximum efiiciency is obtained from combustionduring normal operation. It will also be seen that within limits my oil65 burner may supply a variable flame while memes maintaining acombustion of maximum efficiency.

The embodiment of the mventlon 1llustrated and described herein has beenselected for the purpose of clearly setting forth the principlesinvolved. It will be apparent, however, that theinvention is susceptibleof being modified to meet the different conditions encountered in itsuse, and I, therefore, aim to cover by the appended claims all of themodifications within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates, is

1. A mixing device having means for supplying one element of the mixtureand another means for supplying another element of the mixture, adifferential means for operating both of said supply means, and means0perative to cause said differential means to vary the mixture of saidelements on starting.

2. A mixing device having an electric driving motor with a rotor and arotating frame, means for supplying one element of the mixture and othermeans for supplying another element of the mixture, one of said meansbeing connected to be driven by said rotor and the other of said meansbeing connected to be driven by said frame, and means operative to causesaid rotor and rotating frame to have varying speeds to vary theelements of said mixture on starting.

3. A mixing device having a driving motor with a rotor and a rotatinframe, means for supplying one element 0 the mixture and other means forsupplyin another element of the mixture, one of sai means beingconnected to be driven by said rotor and the other of said means beingconnected to be driven by said frame, and means associated withsaidrotor and rotating frame to cause said rotor and rotating frame tovary operation of said supplying means whereby'a different mixture ofthe elements is obtained on starting from the mixture supplied duringoperation after starting.

4. An oil burner having a fuel pump and a blower for supplying oil andair to the combustion chamber, a driving motor having a rotor and arotating frame, said rotor and frame being connected to drive the pumpand blower to provide a mixture of oil and air and means associated withsaid motor for causing said rotor and rotating frame to vary operationof said blower and pump to change the ratio of said oil and air mixtureon starting.

5. An oil burner having separate means for supplving liquid fuel and airfor combustion, and means for differentially controlling said separatemeans and automatic means operative to cause said difl'erential means tovary the mixture of fuel and air during operation of said burner.

6. An oil burner having separate means for supplying liquid fuel and airfor combustion, and automatic means including a differential drive forcontrolling said separate means to provide a relatively rich fuelmixture upon initiating operation of said burner and thereafter decreasethe richness of the fuel mixture.

7. An oil burner having a fuel supplying means and an air supplyingmeans, a device including a differential driving means for operatingsaid fuel supply and air supply means, and means associated with saiddevice for controlling the same to provide a relatively rich fuelmixture upon starting and thereafter to provide a mixture forsubstantially complete combustion.

8. An oil burner having a fuel supplying means and an air supply means,a differential device for operating said fuel supply and air supplymeans, means controlling said differential device to provide a rich fuelmixture upon starting and thereafter to provide a mixture forsubstantially complete combustion, said last means insuring sufficientair for substantially complete combustion of fuel upon shutting down theburner.

9. An oil burner having a fuel supply pump and a blower, an ignitiondevice, a differential driving means, said pump and said driving meansbeing operatively connected, said blower being connected to be driven bysaid driving means and means associated with said bower for increasingthe inertia thereof whereby the speed of the pump is initiallyabnormally high to give an initial rich mixture and the speed of theblower is gradually accelerated and the speed of the pump graduallydecreased to obtain a mixture for substantially complete combustion.

10. An oil burner having a fuel supply pump and an air blower, adifferential driving means operatively connecting said blower and saidpump to supply a mixture for substantially complete combustion duringoperation of said burner, inertia means associated with the blowerwhereby said blower is slowly brought up to running speed uponinitiating operation of the burner and said fuel pump is caused tooperate at more than normal running speed to provide a rich mixture,said blower continuing to rotate due to the inertia means for asufficient length of time to insurecomplete combustion of any oil insuspension upon stopping operation of the burner.

11. An oil burner having a fuel supply pump and a blower, a flywheelconnected with said blower, a differential driving motor having arotating frame and rotor connected respectively to said blower and pumpto drive the same. said blower and pump upon initiating operation of theburner providing a rich fuel mixture to insure ignition, and thereafterfurnishing a mixture for substantially complete combustion.

12. An oil burner having a fuel supply pump and a blower, a flywheelconnected with said blower, a driving motor having a rotating frame androtor connected respectively to drive said blower and pump, said blowerand pump upon initiating operation of the burner providing a rich fuelmixture to insure combustion, and thereafter furnishing a mixture forcombustion of maximum efficiency, said blower upon deenergization ofsaid driving means being maintained operative for a sufficient length oftime by said flywheel to insure complete combustion of oil insuspension.

13. An oil burner having separate means for supplying liquid fuel andair for combustion, and automatic means for differentially controllingsaid separate means to provide a relatively rich fuel mixture uponinitiating operation of said burner and thereafter decrease the richnessof the fuel mixture, and means cooperating with said automaticdifferential means whereby the liquid fuel and air may beproportionately decreased to vary the flame while maintaining'a mixturefor substantially complete combustion.

14. An oil burner having a fuel supplying means and an air supplyingmeans, a means including a differential drive for operating said fuelsupply and an air supply means to provide a mixture for substantiallycomplete combustion, and means cooperating with said differential meanswhereby the fuel supply and air supply may be proportionately decreasedto vary the flame while maintaining said fuel and air mixture forsubstantially complete combustion.

15. An oil burner having a fuel supplying means and an air supplyingmeans, a differential device for operating said fuel supply and an airsupply means to provide a mixture for substantially complete combustion,and a control device for said fuel supply for varying the amount of fuelsupplied by said fuel supplying means to provide avariable flame, saiddifferential device in response to operation of said control devicevarying the speed of said fuel supplying means and said air supplyingmeans to maintain said fuel and air mixture for substantially completecombustion.

16. A burner having a means for supplying one element of a combustiblemixture and other means for supplying another element of the combustiblemixture, means for operating said element supplying means, and othermeans controlling said operating means for causing one of said supplyingmeans to initially furnish a large quantity of one element which isgradually decreased to a predetermined smaller quantity for providing apre determined mixture and for causing the other of said supplying meansto gradually increase the quantity of the other element from a smallquantity to a predetermined larger quantity for providing saidpredetermined mixture.

17. An oil burner having a fuel supplying means and an air supplyingmeans, means for operating said fuel supplying means and said airsupplying means to provide a combustible mixture, and other meanscontrolling said operating means for causing said fuel supplying meansto initially deliver a large quantity of fuel which is graduallydecreased to a predetermined smaller quantity to provide a predeterminedmixture of fuel and air and for causing said air supplying means togradual- 1y increase the quantity of air delivered from a small quantityto a predetermined larger quantity to provide said predetermined mixtureof the fuel and air.

18. A burner having a fuel pump and a air pump, means for operating saidfuel and air pumps, means controlling said operating means to cause saidfuel pump to initially operate at a speed greater than normal speedwhereby a large'quantity of fuel is delivered, the speed of said pumpbeing gradually decreased to normal operating speed to deliver apredetermined quantity of fuel, said control means causing said drivingmeans to graduallyvincrease the speed of said airpulnp from a very slowspeed to a normal speed to gradually increase the air supply from asmall quantity to a predetermined larger quantity.

In witness whereof, I have hereunto set my hand.

JOHN EATON.

